Centrifugal fans are used in a wide range of applications from commercial building ventilation to industrial dust-collection systems. The fan wheel, or impeller, can come in different designs depending on the chosen application. Conventional impellers can comprise a front plate, a back plate, and a plurality of blades positioned between and connected to the front and back plates. The impeller is operatively associated with a conventional driving means which rotates the impeller thereby creating centrifugal force in an radial direction relative to the impellers axis of rotation. Air enters through a side of the impeller and exits the impeller in the direction of the centrifugal force. In some impellers, the blades tend to be thicker and heavier than blades of other impeller designs, and can therefore be used in heavier duty applications in which the air being moved contains contaminants that can damage lighter weight impeller blades. Such impellers may include brace plates which are positioned between and connected to the blades. During operation, the blades have a tendency to flex in the direction of centrifugal force. The brace plates prevent the blades from flexing, which in turn causes the brace plates to flex in a direction generally perpendicular to the direction of centrifugal force and creating stress in the brace plate. Disadvantageously, high duty cycling and operation at higher temperatures have, at times, resulted in fatigue cracking in the brace plates.
It would be highly desirable to provide an impeller that has heavy blades for use in applications with airborne contaminants, and that can also resist the stresses from high duty cycling that conventional impellers fail under while also providing satisfactory air performance capabilities thereby increasing the life cycle of the impeller.